Answer: Read about the topic of the discussion.
Explanation: Preparation is one of the most important aspect of a group discussion, and how do you prepare? By reading about the topic of the discussion before hand so as to get a Broadview of the topic, By also reading on various topics, because you can never tell when the subject would or might be changed. Be an active reader not a passive reader who only reads to understand a subject or topic. But an active reader who not only understands but raises opinion and questions. As this is critical in a group discussion to either counter or support a view or opinion.